Breast conserving therapy is by far the preferred choice of the majority of women with early stage breast carcinoma. The recommended options for radiation treatment following lumpectomy are external beam therapy and, in certain cases, an additional local dose by brachytherapy. Avoiding local occurrence is, naturally, the primary goal, but cosmesis and patient comfort are of critical importance. Traditional 192Ir wires and the newer 125I seeds, inserted into the tumor bed are not optimized for breast brachytherapy. These devices are generic products and were not designed with women's health and welfare as the primary objective. This application describes the development of small diameter flexible coiled 103Pd wire source that constrains radiation field to the tumor bed and its margin. The low energy of the source will broaden the indication for use, as it can be used for more superficial tumor beds. It will reduce the need for patient isolation. The extended linear source provides a more homogeneous dose distribution, eliminates hot and cold spots, ameliorates the high contact dose and the possibility of tissue (fat) necrosis. The fine (0.35-mm diameter) profile of the source should improve patient comfort, minimize scar tissue, and improve cosmesis. The effortless source assembly will minimize unintentional exposure to the health care workers. PROPOSED COMMERCIAL APPLICATIONS: The role of brachytherapy for treatment of carcinoma of the breast is evolving. At its height, the number of women receiving breast brachytherapy has been reported to be as high as 26,000 cases/year. A serious impediment for the breast brachytherapy modality has been the absence of an optimal source that delivers a reliable and adequate dose to the intended site but minimizes radiation complications to adjacent organs and attending healthcare workers. The source described in this application is believed to address many of these concerns and create major opportunity for brachytherapy of the breast and other organs.